RIO DE JANEIRO - Singapore sailor Colin Cheng lies in 15th place after four races so far at the Marina da Gloria.

The Laser sailor started off his regatta well, with a fifth place in the opening race, and followed with a 20th, 13th and 18th place in subsequent races.

With 46 entries in the Laser class, the event has the largest fleet across all classes contested at the Olympics. The class is also one of the most competitive classes.

Cheng, competing in his second Olympics, finished 15th overall at the 2012 London Games, Singapore's best showing at this level.

Sailors in the Laser Radial, men's and women's RS:X have also begun competition.

Elizabeth Yin is 25th out of 37 in the Laser Radial after four races.

In the windsurfing classes, Leonard Ong is 34th out of 36 entries after six races. Audrey Yong is 24th out of 26 in her category.

Singapore's sailors in the women's 470 and mixed multi-hull Nacra 17 will compete in their first races on Wednesday (Brazil time).